Don't go to the Richmond Plaza -- or any other such dive. It will limit your options in ladies.
A number of motels/hotels in Ottawa offer "day rates" -- reduced rates if you check in after a certain time in the morning and check out after a certain time in the afternoon. They aren't "hourly" but they are a good deal. When I was younger and used to travel around by car, I always scoped out day rate hotels -- it was easier for me to drive at night (I see better at night) and it was definitely easier and less traffic for me to drive at night. During the day, I'd pay the reduced rate, check in, have a shower, a bite to eat, a snooze, and be back on the road again just as the traffic and temperatures were winding down.
I was going to call around and check out some day rates for Ottawa -- but then I hit a very busy stretch and a hard drive crash, and... you know! I'll get to it yet! But basically, just call any decent looking business class hotel/motel around where you want to be and ask for day rates. Lots of travelers like me prefer them, so they won't immediately make assumptions. Probably more than half of all hotels have them.
Stay away from the obvious "dives" though -- they're not usually a much better deal than day-rate hotels, many SPs avoid them, and you never know what kind of fleas/lice you might pick up -- let alone what kind of creeps you might encounter hanging around the place. When my husband and I first met, we returned to Toronto from touring, and while I went off to visit a client, I asked him to get us a room -- but I told him not to spend too much. I was floored when I learned that he got us some flea-bitten motel on Toronto's Lakeshore. I think I spent more in Lysol and cleaners to make the place safe enough to go to sleep in that night than the room cost. The next day, we checked out and I got us another room at a clean, no-frills business class hotel that actually cost us less than the "apparent" deal. Just goes to show!
Good luck!
..c..